1. Field of the Invention
This invention relates generally to transportable lifts for automobiles, and more particularly to an apparatus for lifting a vehicle and supporting the vehicle at the lifted position.
2. Description of the Related Art
Maintenance of vehicles such as automobiles and trucks requires access to the underside of the vehicles in order to permit repair or alteration of parts, such as wheel assemblies, suspension, transmissions, brakes and the like. In order to access such areas, a mechanic will typically employ one or more lifting devices in concert or sequentially to move part or the entire vehicle to a raised position.
Once the vehicle has been raised to a desired height for access, rigid stands may be positioned beneath the vehicle to support it and the lifting devices may be removed. Such rigid stands are used because rigid stands provide better support and do not permit vertical shifting of the vehicle.
Vehicle lifts, which typically lift the vehicle frame, may create several problems. Typical lifting devices apply lifting force to the vehicle frame. Use of lifting devices may be impeded or prevented due to the location of the lifting point relative to the exterior of the vehicle as well as the clearance between the ground and the frame due to vehicle construction, vehicle suspension modification, ground effects or the like. Lifting the vehicle from a point other than an appropriate lifting point may cause damage to vehicle components. Lifting the vehicle at the frame may damage ground effects structures, which extend downward from the body to a point below the frame. It may also damage the appearance of the frame or undercarriage in cases where a pristine frame or undercarriage is desired.
As an alternative to vehicle lifts, a vehicle lift that contacts the lower portion of the tire-and-wheel assembly may be used. Lifting the vehicle from the tire-and-wheel assembly provides an additional benefit where the vehicle is particularly close to the ground and there is little space for insertion of a lifting device. Lifting the vehicle from the tire-and-wheel assembly more quickly provides additional clearance, as there is no delay while the suspension travels to its maximum deflection and requires less travel by the lifting device. Such tire-and-wheel lifting devices typically employ a fork to engage to the front and rear of the tire-and-wheel assembly, such that the tire-and-wheel assembly has relatively even pressure on both the front and rear half, so it will not have a tendency to roll off the tines of the fork.
Both such vehicle lifts may be permanently mounted or may be portable. The use of portable vehicle lifts is essential for persons performing such work outside of a professional garage. Often times portable vehicle lifts include a base too large to be inserted under a vehicle, which is close to the ground. A large base is intended to prevent the lift from tilting during vehicle lifting.
Tire-and-wheel assembly engaging vehicle lifts are known in the art. U.S. Pat. No. 5,954,160, issued to Wells, Sr., et al. on Sep. 21, 1999, discloses a tire-and-wheel assembly engaging lift for raising the entire vehicle comprising, inter alia, a pair of arms, each ending in a set of tire-and-wheel assembly engaging adapters, pivotally attached to a vertically-adjustable carriage wherein each arm may be elongated and adjusted so each fork may engage the lower exterior of the respective tire-and-wheel assembly. U.S. Pat. No. 5,911,408, issued to Berends et al. on Jun. 15, 1999, discloses a transportable lift for raising a single tire-and-wheel assembly of a vehicle, comprising, inter alia, a stand, a carriage having a set of forks attached to said stand capable of vertical movement, a base having transporting wheels and a forward extending section adjacent the forks and a means to disengage the transporting wheels. U.S. Pat. No. 5,484,134, issued to Francis on Jan. 16, 1996, discloses a vehicle lift and stand comprising, inter alia, a base having a vertical post and a forward extending section surrounding the edges of the tire-and-wheel assembly, a cylinder mounted on said vertical post with a piston and cylinder means for moving a tire-and-wheel assembly cradle, a pawl and ratchet system for restricting motion to the intended direction only, and a means to lock the carriage at a particular height comprising a pin though a hole in the post. U.S. Pat. No. 5,184,930, issued to Kuhn on Feb. 9, 1993, discloses a system for lifting a vehicle comprising, inter alia, two jacks, two carriages mounted on posts, each carriage engaging one tire-and-wheel assembly with a fork, each post having a forward extending section surrounding the edges of the tire-and-wheel assembly, and a system to power said jacks. U.S. Pat. No. 3,647,183, issued Mar. 7, 1972 to Rishovd, discloses a system for raising a vehicle comprising, inter alia, a lift member on a vertical column having teeth to engage a pawl for restricted up or down motion, a valve to drive a piston and cylinder assembly to vertical motion and a base having a forward extending section surrounding the edges of the tire-and-wheel assembly.